Control over Nav Rows

Hi,

I've added control over the number of rows, size, and how they are ordered. This helps build cases where you need to break events into more than 3 full / 6 half sized rows - which is currently hard coded. Here is a short summary of the changes:
1. Fixed recursive merging of config object, allows setting properties under `config.nav` and below
2. Remove hard coded calculations of row size and count
3. Added support for pre-ordered tagged rows via `tags` node in JSON
4. Fixed handling of `seconds`as intervals - one of my use cases was a sequence that lasts only 2 minutes
5. Added example files (and tested the existing ones still work)
6. Updated README file

`*** IMPORTANT ***` - I did not create a minified build as the `fab build` command does not work for me - I also opened an issue #546 for that. If you merge this branch you will also need to create a build (or better yet help my issue and command me to do it ;)

Hope you find this useful 
Ron